1. Field of the Invention
The present invention relates to a method of correcting componential concentration, which is measured for analyzing expiration of a subject, with an analyzer such as a gas chromatograph, and an analyzer for implementing such a method.
2. Description of the Background Art
It has been recognized that expiration of a sick person also contains information about the persons, disease, and a study is now being made on analysis of such expiration in a clinical test which is made for diagnosing, curing or preventing the disease.
In expiration which is subjected to analysis, a part called end-tidal air is most suitably employed as a sample for the analyzer. The end-tidal air is the remaining part of the expiration from which an initial part containing air from a dead space is discarded. Since the end-tidal air contains only alveolar air with homogeneous concentration of expiration components, it is excellent as a specimen. In an expiration test, therefore, the end-tidal air is measured as the most reliable specimen expressing the state of the subject, while a specific apparatus is required for collecting the end-tidal air.
On the other hand, it may be impossible or difficult to test the end-tidal air, for some reason or other. For example, it is difficult to collect the end-tidal air from a subject such as a baby, a child, a soporose patient or an unconscious patient. If the subject is healthy but old, for example, it may also be difficult to test the end-tidal air in consideration of the subject's physical strength.
In order to readily collect expiration in a painless manner, a collecting mask or hood is applied to the subject for temporarily collecting the subject's expiration in a bag or directly guiding the same to an analyzer. However, the collecting mask, which can be prepared from that for supplying oxygen to a patient, cannot be brought into close contact with the subject in an airtight manner because the mask itself has holes for communicating with ambient air. When the expiration is collected through such a collecting mask, ambient air is inevitably mixed into the expiration. While it is also possible to collect the expiration by applying a mask or a hood to or covering the respiratory organ, ambient air is also inevitably mixed into the expiration since the respiratory organ cannot be sealed.
Thus, the expiration which is collected by a conventional method contains not only the alveolar air but air from the dead space and ambient air, unless the same is collected by a specific method.